The severe thunderstorm watch that was in place for Barrie, Collingwood and Hillsdale, Ont., has ended.

Police say the collision is believed to have occurred when the driver of the motorcycle lost control of his vehicle.

According to officials, there are four confirmed cases in the area, two of which are not linked to one another.

The federal weather agency says conditions are "favourable" for the development of severe thunderstorms that may be capable of producing strong winds, heavy rain and large hail.

Daytime high temperatures that are more than 30 C are expected, with humidex values predicted to be in the high 30s to low 40s.

The federal weather agency says a period of hot weather will begin Tuesday, with daytime high temperatures reaching in excess of 30 C.

The main threats are wind gusts of 100 kilometres per hour that may cause local power outages and torrential downpours.

The body has been positively identified as Patrick Joseph Horgan, who had last spoke to his family on May 14.

Northwest winds with frequent gusts of 70 km/h will continue into Tuesday evening, bringing in an "unseasonably cold air mass" from the Arctic.

"Travel will be hazardous at times, and motorists are advised to change their travel plans accordingly," Environment Canada says. "Local whiteout conditions may occur."